Beta-lactams SB 212047 and SB 216754 are irreversible, time-dependent inhibitors of coenzyme A-independent transacylase.
The enzyme coenzyme A-independent transacylase (CoA-IT) has been demonstrated to be the key mediator of arachidonate remodeling, a process that moves arachidonate into 1-ether-containing phospholipids. Blockade of CoA-IT by reversible inhibitors has been shown to block the release of arachidonate in stimulated neutrophils and inhibit the production of eicosanoids and platelet-activating factor. We describe novel inhibitors of CoA-IT activity that contain a beta-lactam nucleus. beta-Lactams were investigated as potential mechanism-based inhibitors of CoA-IT on the basis of the expected formation of an acyl-enzyme intermediate complex. Two beta-lactams, SB 212047 and SB 216754, were shown to be specific, time-dependent inhibitors of CoA-IT activity (IC50 = 6 and 20 microM, respectively, with a 10-min pretreatment time). Extensive washing and dilution could not remove the inhibition, suggesting it was irreversible. In stimulated human monocytes, SB 216754 decreased the production of eicosanoids in a time-dependent manner. In an in vivo model of phorbol ester-induced ear inflammation, SB 216754 was able to inhibit indices of both edema and cell infiltration. Taken together, the results support two hypotheses: 1) CoA-IT activity is important for the production of inflammatory lipid mediators in stimulated cells and in vivo and 2) the mechanism by which CoA-IT acts to transfer arachidonate is through an acyl-enzyme intermediate.
Winkler
J D
JD
Department of Immunopharmacology, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19406, USA. james_d_winkler@sbphrd.com
Sung
C M
CM
Chabot-Flecher
M
M
Griswold
D E
DE
Marshall
L A
LA
Chilton
F H
FH
Bondinell
W
W
Mayer
R J
RJ
D000123:Acetyltransferases / Q000037:antagonists & inhibitors*; D051051:Acyl-Carrier Protein S-Acetyltransferase; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D002460:Cell Line; D015777:Eicosanoids / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D007769:Lactams; D051379:Mice; D008807:Mice, Inbred BALB C; D008861:Microsomes / Q000201:enzymology; D009504:Neutrophils / Q000201:enzymology; D010972:Platelet Activating Factor / Q000378:metabolism; D047090:beta-Lactams / Q000494:pharmacology*
D000893:Anti-Inflammatory Agents; D015777:Eicosanoids; D004791:Enzyme Inhibitors; D007769:Lactams; D010972:Platelet Activating Factor; C110619:SB-212047; C110620:SB-216754; D047090:beta-Lactams; D000123:Acetyltransferases; D051051:Acyl-Carrier Protein S-Acetyltransferase